PROJECT SUMMARY/ ABSTRACT Although universal early childhood developmental screening is recommended by the American Academy of Pediatrics, ample evidence suggests that child health providers are not meeting those recommendations, and many early developmental delays are being missed. Additional evidence suggests that both providers and parents struggle to navigate the early childhood developmental system of care, with few high-risk children actually getting referred, and fewer still ultimately receiving services. The gaps in care processes have created gaps in evidence linking developmental screening to developmental outcomes, leading the US Preventive Services Task Force to state that there is not enough evidence to recommend for or against universal screening for speech and language delays or Autism Spectrum Disorders. The proposed project is a randomized controlled trial of a telephone-based early childhood developmental care coordination system, in partnership with 2-1-1 Los Angeles County (211LA), part of a national network of 2-1-1 call centers covering 93% of the US population. We will test the effectiveness of 211LA in increasing referrals for developmental evaluation, increasing the numbers of children deemed eligible for services, and increasing the number of children actually receiving interventions. The trial will enroll 800 children ages 1-3 years who receive well-child care at one of 10 partner clinic sites. We will conduct developmental screening on all children using the Parental Evaluation of Developmental Status (PEDS) Online system, and randomize children 1:1 into intervention (connection to 211LA for developmental care coordination + usual care) or control (usual care alone, with developmental care coordination conducted by clinic staff). Primary outcomes will include referrals to early intervention evaluations, eligibility for intervention services, and receipt of services. We will measure these outcomes through parent report, medical record review, and 211LA data, at 6 months after enrollment. For children with elevated developmental risk based on the PEDS Online results, we will assess development using the gold-standard Brigance Inventory of Early Development III (Brigance), conducted at baseline and 24 months after enrollment. For all children, we will administer the language and cognitive subscales of the Brigance at baseline, 12 months and 24 months, to evaluate development over time in the two groups. We will measure behavioral outcomes for all children using the externalizing behavior subscale of the Child Behavior Checklist. Expected findings include higher rates of referrals, eligibility, and receipt of intervention services among intervention group participants, and greater developmental gains among children in the intervention group. We will also examine the costs of the program in relation to these outcomes, to estimate the costs and potential long-term benefits of this model. If effective, the model has the potential to disseminate rapidly throughout the 2-1-1 network and transform developmental care coordination in the US.